At present, a traffic information provision service supplies traffic jam information, incident/restriction information about such as accidents and lane restrictions, service area/parking area occupancy information, and various other traffic information. Car navigation devices calculate a route to a destination in accordance with the traffic jam information, and indicate a route bypassing congested roads, and accurately estimate the time of arrival at the destination, thereby improving convenience to the user. Further, the car navigation devices can display the information about the locations of accidents and faulty vehicles and the locations and periods of constructions and restrictions, which is included in the incident/restriction information, to convey relevant traffic information to the user and indicate a route bypassing the sites of incidents.
However, the update of incident/restriction information is delayed because the traffic information provision service manually inputs and sets information after receipt of the information about encountered/resolved accidents. Therefore, the navigation devices cannot select a road running through the site of an incident as a route even when the incident is actually resolved.
JP-A-2005-285108 disclose a system that detects an obstacle on a road by using travel path data collected from vehicles and provides detection results to the vehicles as obstacle information. This system can detect an accident, restriction, or other contingency (hereinafter referred to as an incident) from the travel path data to obtain accurate information about not only an obstacle but also the occurrence and resolution date/time and the location of an incident.